/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xpath.axes;

import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xml.dtm.DTMFilter;
import wx.xml.xalan.xpath.XPathContext;
import wx.xml.xalan.xpath.compiler.Compiler;

/**
 * This class implements an optimized iterator for
 * "node()" patterns, that is, any children of the
 * context node.
 *
 * @xsl.usage advanced
 * @see wx.xml.xalan.xpath.axes.LocPathIterator
 */
public class ChildIterator extends LocPathIterator {
    static final long serialVersionUID = -6935428015142993583L;

    /**
     * Create a ChildIterator object.
     *
     * @param compiler A reference to the Compiler that contains the op map.
     * @param opPos    The position within the op map, which contains the
     *                 location path expression for this itterator.
     * @param analysis Analysis bits of the entire pattern.
     * @throws javax.xml.transform.TransformerException
     */
    ChildIterator(Compiler compiler, int opPos, int analysis)
        throws javax.xml.transform.TransformerException {
        super(compiler, opPos, analysis, false);

        // This iterator matches all kinds of nodes
        initNodeTest(DTMFilter.SHOW_ALL);
    }

    /**
     * Return the first node out of the nodeset, if this expression is
     * a nodeset expression.  This is the default implementation for
     * nodesets.
     * <p>WARNING: Do not mutate this class from this function!</p>
     *
     * @param xctxt The XPath runtime context.
     * @return the first node out of the nodeset, or DTM.NULL.
     */
    public int asNode(XPathContext xctxt)
        throws javax.xml.transform.TransformerException {
        int current = xctxt.getCurrentNode();

        DTM dtm = xctxt.getDTM(current);

        return dtm.getFirstChild(current);
    }

    /**
     * Returns the next node in the set and advances the position of the
     * iterator in the set. After a NodeIterator is created, the first call
     * to nextNode() returns the first node in the set.
     *
     * @return The next <code>Node</code> in the set being iterated over, or
     * <code>null</code> if there are no more members in that set.
     */
    public int nextNode() {
        if (m_foundLast)
            return DTM.NULL;

        int next;

        m_lastFetched = next = (DTM.NULL == m_lastFetched)
                               ? m_cdtm.getFirstChild(m_context)
                               : m_cdtm.getNextSibling(m_lastFetched);

        // m_lastFetched = next;
        if (DTM.NULL != next) {
            m_pos++;
            return next;
        } else {
            m_foundLast = true;

            return DTM.NULL;
        }
    }

    /**
     * Returns the axis being iterated, if it is known.
     *
     * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
     * types.
     */
    public int getAxis() {
        return wx.xml.xalan.xml.dtm.Axis.CHILD;
    }


}
